This invention relates to polymers prepared from 1,1-substituted arylethylene monomers, and processes for preparing them.
Thermoset resins are compositions which solidify irreversibly upon curing. Such resins are useful in many engineering applications such as coatings, structural laminates, adhesives, films, and composites. Desirable physical properties include enhanced chemical resistance, a high glass transition temperature (hereinafter Tg), high tensile strength, high temperature resistance, electroinsulative or electroconductive properties, and oxidative stability.
Many aerospace manufacturers require that composite materials retain greater than 50 to 60 percent of their strength at 325.degree. F. after being exposed to boiling water for prolonged periods of time.
Bismaleimides are commercially available monomers currently being evaluated as a potential matrix resin for high performance structural composites where excellent thermal and thermooxidative stability are required. Unfortunately, polymers derived from polymaleimides are susceptible to degradation of their physical properties by moisture as well as many common organic solvents. Polymaleimides have good thermal stability but are extremely brittle indicating they have a high degree of crosslinking.
It would be desirable to have new thermoset polymers with improved physical properties or improved combinations of physical properties compared to those of known bismaleimide homopolymers. Some of these properties include enhanced oxidative stability (0% weight loss at 350.degree. C.) and a high Tg (greater than 200.degree. C.). It would be further desirable to have a polymer system with a low polymerization onset temperature thereby allowing removal of the polymer from the mold after a preliminary curing period followed by transfer to an oven, a less expensive piece of equipment, for additional curing; thus making the mold, a more expensive piece of equipment, available for the next polymerization run. It would be still further desirable for such polymer systems to have a polymerization onset temperature lower than about 150.degree. C.